Re: buffercache/bgwriter

On 23 March 2011 16:36, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> On Wed, Mar 23, 2011 at 6:19 AM, Jochen Erwied
> <jochen(at)pgsql-performance(dot)erwied(dot)eu> wrote:
> > Wednesday, March 23, 2011, 1:51:31 PM you wrote:
> >
> > [rearranged for quoting]
> >
> >> background writer stats
> >> checkpoints_timed | checkpoints_req | buffers_checkpoint |
> buffers_clean |
> >> maxwritten_clean | buffers_backend | buffers_alloc
> >>
> -------------------+-----------------+--------------------+---------------+------------------+-----------------+---------------
> >> 3 | 0 | 99754 |
> 0
> >> | 0 | 115307 | 246173
> >> (1 row)
> >
> > buffers_clean = 0 ?!
> >
> >> But I don't understand how postgres is unable to fetch a free buffer.
> >> Does any body have an idea?
> >
> > Somehow looks like the bgwriter is completely disabled. How are the
> > relevant settings in your postgresql.conf?
>
> I suspect the work load is entirely bulk inserts, and is using a
> Buffer Access Strategy. By design, bulk inserts generally write out
> their own buffers.
>
> Cheers,
>
> Jeff
>

Yes. that's true. We are converting databases from one schema into another
with a lot of computing in between.
But most of the written data is accessed soon for other conversions.
OK. That sounds very simple and thus trustable ;).

So everything is fine and there is no need/potential for optimization?

Best...
Uwe